GREENBELT, Maryland USA — Nicholas Salem is only 7 years old, but he's already a seasoned rocketeer.

About 30 flights a year since he was 4 have taught him a thing or two about what makes a rocket fly. He talks about connecting wires, three-stage boosters and struggling with parachutes.

It's a story of successful launches—and a few crashes.

"I just have fun buying rockets, making them and flying them," he says. "I never get tired of it, and I like the sound when they launch."

Nicholas has come to NASA's Goddard Space Flight Center with a co-engineer—his dad, Norman—and a six-foot model rocket he calls "the Mean Machine." Twice a month, Goddard invites rocketeers such as the Salems to launch their model rockets in an area behind the visitor center; would-be rocketeers also are welcome to come and marvel at the rockets soaring into the sky.

On this blustery Sunday, however, the Mean Machine will stay earthbound. Like real rockets, model ones are sensitive to weather conditions, and, at 30 to 40 mph, the wind is too strong for launches.

Most model rockets, sold in hobby and toy stores, are made of plastic, cardboard or balsa wood. They come in kits, with separate pieces—a nose cone, fins, a body tube, a parachute and connecting rings—that are glued together and decorated with paint and stickers. A small motor fueled by black powder (similar to fireworks explosives) fits into the base. Then the rocket is set on a launch pad and wired to a pair of batteries. After that, all there is left is the countdown.

"You don't need to be a rocket scientist to fly a model rocket," says Ed Pearson, the volunteer in charge of Goddard's model rocket launches. He's been launching rockets at Goddard since 1976, when a number of model rocket clubs volunteered their time and expertise to start the program.

According to Pearson, a standard rocket kit costs about $8 and can be assembled in less than 40 minutes. And the rockets—assuming nothing goes wrong—can be used again and again. Once a rocket reaches the highest point of its flight, it deploys a parachute or streamers that bring it safely back to earth. Only the motor must be replaced before the rocket is ready for another takeoff.

"Model rockets are not like fireworks or anything like that," Pearson explains. "They are designed for multiple flights. And some of the rockets we have—like models of the Saturn 5—have flown more than a hundred times."

Model rockets can fly several thousand feet into the air, but the rockets launched at Goddard reach only 300 to 400 feet. It's a question of putting safety first, Pearson says. To be on the safe side, launch organizers also use a remote-controlled electric switch—no matches—and don't allow the rocketeers to use homemade motors. If a rocket does explode, it doesn't pose much of a danger: Because it is made of lightweight material, it just turns into confetti.

"I don't know of anyone who has ever been killed with a model rocket," Pearson says. "I've heard reports of people who have broken arms from falling out of trees to recover these, because they do land in trees. But it's got a really good safety record."

Model rocketry is not just a children's game. For many adult rocketeers, it's a serious sport. Many national and international competitions award prizes for the rockets that can reach the highest altitude and those that can stay in the air for the longest time—among other things. The competitors don't use kits but spend hours designing and building their own rockets from scratch.

"There is a lot of technique involved in building the rockets to get the highest performance and come up with new designs," explains Chris Kidwell, a PhD chemistry student at the University of Maryland and a volunteer at Goddard. "We've got about 3,000 or so people who compete all the way across the country. And that's what makes it really fun—trying to see how well you can do compared to other people."

But for the children at Goddard, the fun is just seeing the rockets take off.

"It's like the Fourth of July to them," Norman Salem says. "It's safer than fireworks, but it gives the kids the same thrill. And they learn a lot."

The Goddard Space Flight Center Visitor Center is on Soil Conservation Road, Building 88, in Greenbelt. The center hosts model rocket launches at 1 p.m. on the first and third Sundays of the month, weather permitting. Admission is free. For more information, call 301-286-8981.

Copyright © 1999, The Washington Post Company.